The present invention relates to a video signal processing circuit of a video signal recorder/reproducer, and particularly to a video signal processing circuit of a video signal recorder/reproducer which includes an improved adaptive folding circuit capable of lowering the signal level of a high frequency component to be folded during recording to control the signal level of an unnecessary high frequency component in processing a luma signal of the video signal, and an improved adaptive unfolding circuit capable of restoring an unfolded high frequency component signal during reproduction.
In recent years, video signal processing circuits have used folding and unfolding circuits to increase the amount of information which can be accommodated by a predetermined narrow band channel so that the high frequency components of a video signal are folded around a selected folding frequency. Then, the folded high frequency component is placed within a specific spectral gap in the video signal.
However, in the above-mentioned video signal processing technique of a video signal recording/reproducing system, the signal level of the high frequency component folded into the low frequency component is too high to be properly eliminated when unfolding is performed in a conventional unfolding circuit during reproduction. Thus, the image quality may be damaged during the unfolding process.
Moreover, when the video signal with the high frequency component folded into the low frequency component is reproduced by a conventional reproduction device without an unfolding circuit, the high frequency component folded into the low frequency component during the recording process is useless and furthermore, creates noise in the low frequency component which detrimentally effects image quality. Accordingly, the conventional reproducer reproduces the image with noise.